Modern vehicles include complex electric networks for performing various functions. Conventional vehicles having internal combustion engines include a low-voltage (“LV”) battery (e.g., 12V-24V) for supplying energy to various LV loads such as ECUs, sensors, actuators, etc. Hybrid and electric vehicles (i.e., vehicles including an electric traction motor) include a high-voltage (“HV”) battery for supplying energy to various HV loads including the inverter that drives the traction motor. The HV battery may also supply energy to a DC-DC converter in order to supply energy to LV loads. Alternatively or additionally, hybrid and electric vehicles may further include a LV battery for supplying energy to LV loads.
Such vehicle networks including a LV battery and/or a HV battery typically include an electronic module for monitoring the performance and state of the battery. This electronic module is typically referred to as a battery monitor or the like. The battery monitor is configured to measure the battery voltage and the battery current.
The battery monitor typically employs a current sensing shunt for measuring the battery current. The current sensing shunt is a resistor. Due to aging and use, the resistance of the current sensing shunt may change. In this case, the measurement of the battery current by the battery monitor may have an unacceptable error. Therefore, it is beneficial to provide some mechanism for verifying that the battery current is measured within certain accuracy.
One possible solution (used in testers) is to have an external circuitry deliver a calibrated reference current to verify if the battery monitor is accurately measuring the battery current. However, for automotive systems, this procedure is not convenient since the external calibration is not always available and/or it may be difficult to control the accuracy of this external circuit.